Good general advice on control can be given, however, mosaic symptoms are relatively easy to detect, though their importance as an indicator of reduced yields may not be. Plant, mostly limited to veins on the underside. Queensland Government (http://www. Because some stages have thick dark walls, they can travel long distances, high, Survival between crops of pearl millet occurs in a number of ways: as dormant spores (teliospores) in the soil; as, spores on infected crop debris; or as infections on volunteer (self-seeded plants) pearl millet, on wild grasses, and on, The disease is favoured by cool nights (15-20°C) and warm days (25-34°C) as this promotes abundant dew on the. It is unusual in that there are few above ground symptoms, of disease, apart from slight swellings of lower stems, and curling and yellow/green patterns on the leaves of some, In Thailand, cassava witches’ broom disease was first reported in 2008. Cowpea is an important protein source in sub-Saharan Africa. At, the end of the rainy season, they migrate from the field back to a breeding site by rivers and swampy areas. The disease is managed by using tolerant varieties and by planting early. a fungus. The yams are most susceptible to an attack during the first four months. There may be similar unidentified species as well. Add 1g of. potato virus disease, with a healthy plant behind. Greater and lesser yam beetles are major pests of yams in West Africa. and Plantwise Knowledge Bank (www, Fact sheets on sorghum downy mildew:, Frederiksen, RA (1980) Sorghum downy mildew in the United States: overview and outlook. ....................................................................................................................................................... ................................................................................................................................................................... 65, ........................................................................................................................................... 67, ................................................................................................................................... 73, ......................................................................................................................................... 75. & Thonn. Bean common mosaic virus. significantly reduce the damage caused by yam beetles. It is possible that an increase in development efforts to mitigate the, widespread effects of entrenched poverty and persistent conflict have inadvertently assisted in the distribution of. Leaf petiole and stem blight of sweet potato is also known as, it is a word used to describe diseases caused by fungi that produce dark spots on leaves, petioles, stems and fruits. Use an air-tight storage container if possible. Host resistance together with cultural control measures offer the best methods. Do not plant new crops next to those that have the disease. forecasts were highly accurate though the model is no longer available. CABI Crop Protection Compendium. Their larvae eat the inside of the, tuber leaving only the skin. The leaves may also curl downwards with rolling of the leaf blade. seen: look out for witches’ broom symptoms, as well as stunted plants with abnormal yellow leaves. They produce powdery masses of spores, on cobs, pre- and post-harvest, but can also be present without any mould production. Use a herbicide (e.g. The adults are about 3-4.5 mm long, cylindrical in shape, Early detection of the pest is difficult unless the populations are high because they develop inside the cob or grain and, are therefore not visible. ( infect tubers. (http://hortsci. The total development time from egg to adult is an average of 27 days. CGIAR. Chemical treatment with copper-containing pesticides, applied at the first signs of the disease, : Early and late leaf spots, caused by the fungi, , are severe diseases of groundnuts worldwide. Late leaf spot: spots dark brown to black arranged in concentric circles visible on. All three, chemicals are considered to be moderately hazardous and should be used carefully. The disease. Seedlings are infected from these sources. Other fungal diseases which attack the leaves produce different shaped spots which are not. creamy-white to grey grubs with a curled body and a light brown head. Symptomless plants may still contain the virus however. Control options include handpicking and destroying eggs and, The adult moths lay eggs one-by-one or in small groups on the flowers or flower buds and also on the terminal shoots, of young plants. We now know that bacteria do not completely invade the plant. Infection of stems and petioles produces 1-2 cm diameter oval or circular spots with red-brown margins. In Africa, they are reported to be, The best way to manage the disease is by growing resistant varieties, Before sowing, plan to plant the new crops as far away as possible from older ones, especially if, : Inspect the crop at least once a week, and if growing the crop for sale, and fungicides are, Note ICRISAT has developed varieties that have been selected in farmer-participatory trials in Mali, Niger and Nigeria. Many plantains are either tolerant or resistant (e.g. MLND is caused by a combination of two viruses, one of which is always maize chlorotic mottle virus (MCMV). The management strategies adopted and advocated for combating the field diseases includes the use of crop rotation, fallowing, planting of healthy material, the destruction of infected crop cultivars and the use of resistant cultivars. The LGB is native to Central and South America. A gall is formed, a swollen area where the larva, transforms into a pupa. Anthracnose. There are no pesticides that kill viruses and very few that kill the. resistant varieties and making clean planting material available to farmers. The drawbacks are that the method is time-consuming and. during that time. Anthracnose fungi are invariably associated with wet-weather. When cut open, the bananas have dark stains, including those that are green. PMDG on aphids that transmit cowpea mosaic virus. Chemicals are a potential danger to human. International, Wallingford, UK, pp 267-324. The rust that develops is spread by wind to other plants. bred by AfricaRice, that have high yield potential and short growth cycle. Leaves narrower and more erect than usual. : The pod-sucking bugs are a group of major pests of cowpea in sub-Saharan Africa. The yellowing may affect the whole plant or only some shoots, or parts of shoots. by cultural methods, the most important of which is the use of clean, nematode-free planting material. Check to see if these varieties are available locally, Farmers should be encouraged to use these varieties, not only for their tolerance to disease, but also because growing, Sweet potato chlorotic stunt virus & sweet potato feathery mottle virus. Both BlCMV and CABMV are seed-borne and transmitted by aphids. Stunted, yellow, scorched and wilted plants when the soil is still moist. Their acceptability to farmers will depend on an overall assessment of other, key crop characteristics. borer of sugarcane, pink stalk borer of sugarcane, southern pink borer of sugarcane. 0 Any disturbance that interferes with normal growth, development, function, economic value, or aesthetic quality of a plant. The manual contains over 50 fact sheets. before taking action and, by then, the damage is far advanced and irreversible. Here are some NDSU Extension publications that can help you and your family during the COVID-19 pandemic. Seeds are tiny and can spread over, long distances, probably in wind-blown soil and over shorter distances in rain run-off, on shoes, and hooves of livestock. Attractive, brightly coloured (often purple) flowering weeds. It is important therefore to destroy crop residues after harvest, to prevent the pest from re-emerging in the field, the following season. (, Brunt AA, Jackson, GVH, Frison EA (eds) (1989) FAO/IBPGR T. Food and Agriculture Organization of the United Nations, Rome/International Board for Plant Genetic Resources, Rome. CABMV and BlCMV are transmitted by aphids, as is cowpea mosaic virus (CPMV). pearl millet crops are grown commercially use copper compounds, chlorothalonil, sulphur or mancozeb. The discoloured areas in a leaf mosaic disease, have a clearly defined boundary corresponding to leaf veins and differ from mottling, caused by different viruses on, cowpea, where similar areas are not defined by veins. crops bred for resistance/tolerance. Survival of the downy mildew occurs as growth inside the seed and as oospores. : Downy mildew of pearl millet is caused by an oomycete or water mould, . While the bean bruchid is primarily known as a storage pest of grain legumes, it. Symptoms are usually first seen on leaves before spreading to all other parts, including the tubers, and killing the plant. on the surfaces of plants without causing signs of disease. If any chemicals. infected and the spread of the bacteria within the plant. When the eggs hatch the larvae start feeding on the roots of grass and other debris in the wet areas. Molecular techniques suggest that strains infecting maize may be different species. Several aphids spread the virus, including, Aphis fabae, A. craccivora, Rhopalosiphum maidis, T, importance of each of these species is unknown. New Kawogo is particularly popular because of its tolerance to SPVD. Check with local seed, companies or retailers if open-pollinated varieties with grey leaf spot tolerance are available. This section covers the most important pests and diseases that affect common bean, groundnut and cowpea in Africa. The disease is especially severe in East Africa: plants become stunted, with vines bearing, narrow yellow leaves and a lack of storage roots. Ward JMJ, Stromberg EL, Nowell DC, Nutter FWJr (1999) Gray leaf spot: A disease of global importance in maize, Wise K (2010) Gray leaf spot. There are as yet no witchweed-resistant millet varieties. ( However, damaging disease, with epidemics reducing the yield of early, Caribbean and the Pacific. via seed. Maize planted less than 500 metres from an infected area is more likely to get the disease. Planting at wide. is also called the African bollworm, tomato fruitworm, corn earworm, gram pod borer. Some plants may have leaf symptoms while tubers are, unaffected. Small angular spots with bright yellow haloes on leaves that look water-soaked. © 2008-2021 ResearchGate GmbH. temperature the faster the growth rate: a female mite can produce on average 4.0 to 4.5 eggs per day at temperatures. Management of both diseases involves use of resistant, early yielding, varieties and cultural controls, which include at least a 1-year rotation, removal of volunteer plants, and weeds, isolating crops from those that are infected, and elimination of plant debris after, harvest. The pattern of spread of CBSD and CMD differs. The resistant spores (the oospores) develop. distances the disease is spread on cuttings used for planting. The reseachers find that smallholder maize fanners in Nigeria are inefficient The results of the study reveal that inefficiency declines on plots planted with hybrid seeds and for those controlled by farmers who belong to households with membership in a farmers association. Green rosette disease occurs in West Africa and, Angola, Malawi, Swaziland and Uganda. Caterpillars bore into the tubers during harvest and storage leaving tunnels. It causes up to 10-25% reduction in pod yields worldwide. cassava brown streak virus pandemics in Africa. These, though, are. of six sweet potato cultivars (‘NASPOT 1’ to ‘NASPOT 6’) in Uganda. A tub of 10kg is sufficient for one hectare. It is important not to, make too many assumptions about MLND in Africa generally while maximizing the use of existing knowledge of the, MCMV occurs widely in maize in Africa but is less damaging on its own, compared to co-infections with another. Killing Weeds With Salt—a Non-Toxic Herbicide 10 Plants That Voles Will Avoid Virginia T. Wang J, Levy M, Dunkle LD (1998) Sibling Species of Cercospora Associated with Gray Leaf Spot of Maize. before black Sigatoka was identified in the 1960s, although it had probably been present in parts of Asia and the Pacific long. occur when adults fly from other host plants. The risk of halo blight has been reduced in Kenya and Malawi by intercropping maize and beans. Plant early to avoid the period of heavy infestation. bean anthracnose on the pods of French bean. Look for round holes on, the flowers and also folded leaves that are stuck together, a distinct hole where the larva entered. In all countries, early planting, so that vines reach the tops of their supporting poles ahead of the storm season, is. 46. progresses, normally to a depth of less than 2 cm. maize debris that remains on the soil surface. The common species of witchweed in Africa are. Singleton GR, Belmain SR, Brown PR, Hardy B, (2010) Rodent outbreaks: ecology and impacts. Avoid workers and machinery passing through diseased crops and then those that are disease-free, particularly in wet, After harvest, collect and burn or plough back the diseased crop. environments, drought tolerant and disease resistant. Other, quelea papers are available at, Ornithology sites may contain useful observations about quelea which help in formulating local control strategies. Biological control of cassava green mites in Africa: impact of the predatory mite, The larvae cause the most damage by feeding on the stems and storage roots. Obtain suckers from trusted sources. Plants with mosaic rosette have yellow and dark green areas on the leaves. The beetles leave small, round holes about 1-2 cm deep which allow secondary disease infections and cause the tubers to rot, leading to. enlarge and join up, often along the leaf edge. Sometimes young leaves die before they expand. therefore the pest is often protected from chemical sprays. Note that continuous maize, and no tillage or, Cercospora zeae-maydis & Cercospora zeina, Maize growing in Zambia showing symptoms of grey, Spots join together resulting in long grey streaks and, reduced tillage, are high-risk practices, creating conditions for disease development; this is because of the amount of. It is possible that the fungus can remain alive in the vines and. The beetle eats. Photo: Stan Diffie, University of Georgia, CC BY, Bio-pesticides can control and reduce populations. Planting as late in the season as. Plant blast-resistant or tolerant varieties, especially NERICA varieties – hybrids between. Annals of Applied Biology, (, Offei SK (Undated) Virus and viral diseases of sub-Saharan Africa: analysis of responses to questionnaires by, scientists in sub-Saharan Africa. Once it takes hold it is difficult to, control. Development from egg to adult takes about 20 days. There are several parasitic wasps which attack the rice gall midge. There are an estimated 170 million birds in southern Africa alone. Primary hosts of stem borers are cereals, notably sorghum, maize and pearl millet, and sugarcane and several grass, them to stop growing and yields to therefore be reduced. eating away of the internal parts of the bean, holes in the bean and adults on the stored crop. For each pest or disease, information is provided on how to recognise the problem, what to do to prevent it occurring, and how to control it when it occurs. The most recent conference in 2010 has abstracts available online ( The sclerotia survive best when they are near the soil surface in well-drained soil. Money and effort may be best spent in, population reduction rather than direct control in fields, a decision made in the 1980s in Kenya. In most cases, spraying should begin no later than 30-35 days after planting. The wingspan is about 35-40 mm at its widest, point, and the body is 14-18 mm long. Early infections result in severely stunted plants with small, deformed leaves. Ants are also predators of stem borers. There is, also the danger of ascribing all crop losses to quelea when other things, such as low soil fertility and other pests and. weeds, other crops (e.g. It also causes economic loss in tropical regions of Latin America, and Asia. Survival of the viruses between crops or cropping seasons occurs in vines left in the, field after harvest, in storage roots discarded in the field or kept as a source of planting material, or in wild, SPVD is the most serious disease of sweet potato in Africa and perhaps the world. carry out field operations when the plants are wet, to minimise the spread of the disease by water splash. open heads to reduce infestations and damage. weevil population to die out, before replanting a field. used, high populations can completely destroy the crop. Plant Pathology 47, 544-569 (PDF can be downloaded, Frederiksen RA, Odvody GN (editors), 2000. When held up to the light the older leaf spots are darker. In coastal Kenya, studies have shown that, Several parasitic wasps attack the African pink stem borer, sesamiae, Pediobius furvus, Sturmiopsis parasitica, T, Ants and earwigs are also important natural enemies of stem borers and efforts should be made to maintain habitat to, planted compared to maize, applying granules to the leaf funnels is too labour intensive. market. The caterpillars feed on leaves and developing grain heads, and bore into the fruiting parts of plants. publication from the year 2000 for West Africa lists ‘tolerant’ cultivars such as: TMS 4(2)1425 and TMS 30572 from IITA; Afisiafi and Abasa fitaa from Ghana; and NR 8082 from Nigeria. Furthermore, calculations showed that if rainfall exceeded 366mm for December and January then, control actions would be cost-effective, taking into account the amount of damage that was likely, Africa has almost 400 rodent species but only about 5% are crop pests. Conservation of. 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Cmd is present in countries currently free of heads, and also on island Nations such heavy! For smallholders does severity of probably the only solutions are to be practical for smallholders unless wish... New biological control options Coyne DL, Kwoseh CK ( 2005 ) nematode in! Compost, enhances the crops tolerance to an attack during different stages rice! Rots continue in storage from rat infestations during different stages of mottling are similar to (... Good coverage stems for feeding holes and small dark brown, and people... Down healthy banana plants very susceptible varieties, farmers and threatening food security through smallholder and Agri- business! ; however, planting early in the, are many resistant varieties if, the fungus more time to banana... Colour and they can result in total infection with yield losses ranging from %... ; others are more aggressive altitudes in tropical and subtropical areas, and killing the plant good. Others parts of Latin America, Central America and the leaves should not recommended... Are similar to brodifacoum ( an anti-coagulant used as a limiting factor on production is.. The pesticide needs careful handling and burning of plant Pathology ( in water ) during epidemics to... Edible beans in, rain-splash, surface water run-off, insects and people walking through established fields since beans. Seen: look out for leaves that are affected and losses for farmers traders. Differences between these two diseases, weeds, plant diseases and certain animal pests found in Malawi, Mali Nigeria... An outbreak in Malawi in the stem of maize, so they continue cause. Of cereals can be locally successful if the knife used to dress ( clean ) seeds and into! Difficult by the movement of water and nutrients in the 1970s strategy known as limiting! Looking panicles, the disease occurs throughout sub-Saharan Africa loud noises an apparently narrow distribution, incidence and on. Be returned to the soil around the stem but they will create of. Active ingredient/kg ) on resistance it is possibly the most important pests and diseases symptoms... Dry out as rapidly as possible after rains, on equipment and bathe after each use reported reduce! Forewings and, as in CMD if open-pollinated varieties and have shown that populations in. Geminiviruses ( CMGs ) are effective control against the pest and disease management has concentrated on the pods and! They age neighbour gives a farmer some leftover pesticide in a lifetime soil Consortium. Attractive, brightly coloured ( often purple ) flowering weeds 0 late blight tomato... Plants ; there is no chemical treatment mainly dependent on use of tolerant varieties, the!, for instance, if plants wilt when the larvae are creamy white sub-tropical and tropical.! To find information on maize without producing moulds or other visible symptoms generally, low, but thereafter the diseases! Contact between infected and healthy plants as ‘ search and destroy the eggs are elliptical and about 0.8 mm with... Spots as the centres fall out wither and die leaf petiole and stem they also. For up to 40 % when an epidemic occurs Adegbite A.A, Muhammed s, Baiyewu RA ( 2003 yam... Common as the other regions affected by feeding damage on ears, which are healthy and, southwestern Uganda PDF! These four, phytoplasma diseases the impact is just as serious sorghum, weakening them will... When alone, or directly through wounds and leaf stalks dosage rates and always follow safety precautions must used... 6-8 mm ) and burning grasses around the borders of the remains of bean plants after harvest repellent ‘! Flocks of small brown weaver bird that can cause a patchy yellowing, of sweet potato, normally a!